1. Field of the Invention
The present invention relates to an inkjet recording apparatus that performs recording by ejecting ink droplets from a plurality of ejecting portions of a recording head, and a novel structure of a cleaning unit for the inkjet recording apparatus.
2. Description of the Related Art
In recent years, inkjet printers have been widely used as printer apparatuses, an increase in speed of printing and an increase in image quality in the printers are in great demand. A common inkjet printer moves an inkjet head in a main-scanning direction and moves printing paper in a sub-scanning direction, and forms a dot-matrix image on the printing paper by using ink droplets ejected from the inkjet head.
In the inkjet printer, minute ink droplets scattering on the surface of the printing paper, powder of paper separated from the surface of the printing paper, etc., easily adhere to the surface of the inkjet head. In this case, the adhering materials hinder ejection of ink droplets and deflect a direction in which the ink droplets are ejected, so that there may be deterioration in printing quality.
Accordingly, to solve such a problem, it is common that an inkjet printer of the present type cleans the surface of an inkjet head by using a wiper to perform wiping. Wiping mechanisms include various structures. For example, in a common type of structure, by controlling an elastic wiper to touch or not to touch the surface of the inkjet head, which is moved in the main-scanning direction, the surface of the inkjet head is wiped by the wiper in one direction such as the main-scanning direction.
In one of various inkjet structures, a nozzle member and a wiring member are provided, for example, on the surface of a head substrate in an integrated form. In an inkjet head having this structure, the nozzle member has a nozzle array in which many ink nozzles are arranged in a sub-scanning direction. Each ink nozzle has a built-in driving element that ejects ink droplets in response to an externally input driving signal.
The wiring member has signal wires formed thereon through which externally input driving signals are transmitted to the driving elements on the nozzle member. Thus, driving signals supplied from the main unit of an inkjet printer are transmitted to the driving elements on the nozzle member by the signal wires on the wiring member.
In the case of producing an inkjet head of the above type, for example, the wiring member, in which a rectangular hole is formed, is provided on the surface of the head substrate, and by inserting the nozzle member into the rectangular hole of the wiring member, the nozzle member is provided on the head substrate. In an inkjet head for color printing, the nozzle member has a plurality of nozzle arrays in the main-scanning direction. Thus, signal wires connecting to the driving elements of the nozzle member are formed, reaching two opposite ends in the sub-scanning direction, and the rectangular hole on the wiring member is formed so that the nozzle member can abut against the rectangular hole at the opposite ends in the sub-scanning direction.
Accordingly, a robot arm that holds and inserts the nozzle member into the rectangular hole must hold the nozzle member from two sides in the main-scanning direction. Thus, the rectangular hole of the wiring member is formed in such a shape that it is positioned away from the two opposite ends of the nozzle member. Also, since the signal wires between the wiring member and the nozzle member are connected by using bonding wires, in order to facilitate the operation of the connection, the wiring member is formed so that its surface is higher than that of the nozzle member.
In the above inkjet head, the surface of the wiring member is higher than that of the nozzle member, and there is a gap between the nozzle member and the wiring member. This may cause a case in which, when the wiper wipes the surface of the wiring member and the surface of the nozzle member, the wiper fails to perform good wiping of the location of the nozzle arrays.
In other words, since the elasticity of the wiper causes the wiper to abut against the surface of the nozzle member, etc., for example, in a case in which the moving speed of the wiper is large, the distance from an end of the nozzle member to the nozzle arrays is small, and a difference in height between the wiring member and the nozzle member is large, an operation of the tip of the wiper which follows the surface of the nozzle member slows down, so that the wiper may jump over the nozzle arrays. Also, in a case in which there is a broad and deep gap between the wiring member and the nozzle member, the wiper collides with an end of the nozzle member after the tip of the wiper falls in the gap, and the collision may cause the tip of the wiper to jump over the nozzle arrays.
To prevent the above defects, for example, the moving speed of the wiper may sufficiently be reduced. However, as described above, the wiper moves in the main-scanning direction in the inkjet head, whereby the wiper relatively moves on the surface of the nozzle member. Thus, a reduction in the moving speed reduces the printing speed of the inkjet printer.
In addition, since the printing speed of the inkjet printer has increased in recent years, the moving speed of the inkjet head has inevitably increased. In other words, since the moving speed of the wiper has also increased, the above wiping defects occur frequently.